1. Field of the Invention:
The present invention relates to N-long chain acyl neutral amino acid esters comprising an ester forming residue of a sterol esterified with the carboxy group of a neutral amino acid, and to a cosmetic or a pharmaceutical preparation for external use each containing such ester(s).
Various kinds of esters have generally been used as materials for the oil-phase in skin and hair cosmetics and in medicines for external application. Further, amino acid type surface active agents of natural origin which are very safe have been used recently. Most of such amino acid type surface active agents are hydrophilic. As oil-soluble amino acid type surface active agents, usable as oil-phase materials for cosmetics and pharmaceuticals, N-lower acyl acidic amino acid diesters, N-long chain acyl neutral amino acid and N, N-di-long chain acyl basic amino acid esters are known.
However, although the known compounds as described above have some degree of emulsifying and hydrating performances, the emulsifying and hydrating actions of N-long chain acyl acidic amino acid higher alcohol diesters are remarkably low. For the improvement of the performance, for example in cosmetics, greater effectiveness is required.
On the other hand, various kinds of sterol esters have hitherto been used as an oil-phase material having excellent emulsifying performance. They have particularly preferred hydrating performance but involve the drawback that the use of cosmetics to which they are blended results in a somewhat heavy feeling.
The problem underlying the present invention is to provide novel ester compounds of oil-soluble N-long chain acyl neutral amino acids which have excellent emulsifying capacity and further to provide cosmetic and external pharmaceutical preparations comprising these novel ester compounds, which have excellent moisturizing action and do not a heavy feeling on the skin.